Well,
That did not seem to work. I changed the basemap to point at a local cache of NAIP imagery that I know for a fact has no branding in it because we built the cache from scratch. I changed it in the map.xml file in a project under the Apps_ArcGIS_Silverlight/Config folder. I also went into the Builder_ArcGIS_Silverlight/App_Data folder and changed the Imagery layer in basemaps.xml and ConfigurationStore.xml to point at our local cache. While this did let me pick our basemap from the default basemaps list within the ArcGIS for Silverlight Viewer application, it is still branded. Perhaps it is hardcoded somewhere in there to force it to be branded if you use the ArcGIS for Silverlight program. I will keep messing around with it as this is mainly an RD project and report any findings. If anyone else has an idea please respond. Thanks.